1. The Field of the Invention
This invention relates generally to input devices for electronic information devices. More specifically, the present invention provides a sensing system and a stylus that is operable in two or three dimensions, and which is utilized to provide input such as lines that represent movement of the stylus within a field of operation, or cursor control for computers and portable information appliances such as laptops, PC tablets, personal digital assistants (PDAs) or other types of electronic appliances such as mobile telephones.
2. Background of the Invention
The state of the art of input devices utilizing a stylus is generally characterized by digitizing tablets or a touchpad. A digitizing tablet is generally a large surface that is used to input data with a stylus that is coupled to the tablet or touchpad. For example, a cable connects the stylus to the tablet, and movement of the stylus is detected or tracked as it moves across the surface of the tablet. The movement is typically portrayed as lines on a display.
The basis of operation for most stylus-based tablets is reliance upon electromagnetic sensors. A magnetic field is formed by electric current that is flowing in a loop. The pen has a coil that picks up this magnetic field and sends it back to a convertor that determines the X and Y position from this data. This type of pen generally requires a tether between the pen and a base device to transfer the data, or the use of an active pen that is battery powered and generates some type of signal that is detectable by the touchpad.
It would therefore be an advantage over the prior art to provide a pen or stylus-based system for data input or cursor control which does not require a tethered stylus or an active pen. It would also be advantageous if the stylus did not require an internal power source to operate.
The prior art also describes using a stylus with personal digital assistants (PDAs). When a stylus requires pressure in order to be detectable, the writing surface of the PDA can be damaged. In addition, the writing area for the stylus is typically very small. It is also difficult to use a stylus when there is no visual feedback or “inking trail” to show the writer what has been written. Inking can also be difficult if there is a delay between stylus movement and the appearance on a display screen of what is being written.
Accordingly, it would be an advantage over the prior art to provide an off-screen inking surface to prevent damage to a PDA screen. It would also be an advantage to provide a larger writing surface for the PDA, as well as visual feedback that is rapid.
The prior art also fails to teach any type of stylus which can operate without making contact with a surface that can detect the presence of the stylus. In other words, the surface being written on is some surface that is capable of detecting the stylus. Accordingly, it would be an advantage to be able to detect and track movement of a stylus on a surface, where the surface is not a stylus detection surface.
The prior art also teaches that some type of sensing surface must be used with a stylus. Accordingly, it would be an advantage over the prior art to provide a stylus which does not require any sensing surface in order to be detectable. It would also be an advantage to therefore enable a stylus to be detectable as it moves within three dimensions.
Another aspect to be addressed is the ability to turn writing on and off. Typically, this type of function has required a sensitive surface, possibly a tether from the pen to another device, or an active pen. Accordingly, it would be an advantage over the prior art to provide a stylus that can be actuated to turn on and off writing-on an associated display, where the stylus is a passive device that does not write on a special sensing surface, and is not physically tethered to another device.
A final aspect of the invention is the ability to implement a stylus for use in a very small area. Consider the mobile telephone user that wants to input and email message and send it. It is a tedious and time consuming task with state of the art input options on cell phones. It would be an advantage over the prior art to provide a very small keyboard that is actuated by the stylus so that it can be used in mobile situations, and with relatively small devices.